U.S. patent number 5,301,742 [Application Number 08/083,851] was granted by the patent office on 1994-04-12 for amorphous alloy strip having a large thickness.
This patent grant is currently assigned to Nippon Steel Corporation. Invention is credited to Tsutomu Ozawa, Takashi Sato, Toshio Yamada.
United States Patent |
5,301,742 |
Sato , et al. |
April 12, 1994 |
Amorphous alloy strip having a large thickness
Abstract
An iron base amorphous alloy strip having a sheet thickness of
from 50 to 150 .mu.m and a sheet width of at least 20 mm. The strip
is produced by a single-roll cooling process and has a fracture
strain of 0.01 or more.
Inventors: |
Sato; Takashi (Kawasaki,
JP), Ozawa; Tsutomu (Kawasaki, JP), Yamada;
Toshio (Kawasaki, JP) |
Assignee: |
Nippon Steel Corporation
(Tokyo, JP)
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Family
ID: |
27288035 |
Appl.
No.: |
08/083,851 |
Filed: |
June 25, 1993 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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762733 |
Sep 17, 1991 |
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537165 |
Jun 11, 1990 |
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373175 |
Jun 28, 1989 |
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102274 |
Sep 28, 1987 |
4865664 |
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797176 |
Nov 8, 1985 |
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672065 |
Nov 16, 1984 |
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Foreign Application Priority Data
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Nov 18, 1983 [JP] |
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58-216287 |
Feb 25, 1984 [JP] |
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59-33335 |
May 31, 1984 [JP] |
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59-112015 |
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Current U.S.
Class: |
164/463;
164/423 |
Current CPC
Class: |
B22D
11/06 (20130101); C21D 8/1211 (20130101); Y10T
428/12431 (20150115); Y10T 428/12438 (20150115) |
Current International
Class: |
B22D
11/06 (20060101); C21D 8/12 (20060101); B22D
011/06 () |
Field of
Search: |
;164/463,423 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0088244 |
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Sep 1983 |
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EP |
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55-18582 |
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Feb 1980 |
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JP |
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Other References
J Appl. Phys. 55(6), Mar. 15, 1984, "Dependence of Some Properties
on Thickness of Smooth Amorphous Metal Alloy," Liebermann et al.
.
IEEE Trans. on Magnetics, vol. Mag-18, No. 6, Nov. 1982, "Effect of
FE-B-Si Composition on Maximum Thickness for Casting Amorphous
Metals", Luborsky et al..
|
Primary Examiner: Lin; Kuang Y.
Attorney, Agent or Firm: Kenyon & Kenyon
Parent Case Text
This application is a continuation of application Ser. No.
07/762,733 filed on Sep. 17, 1991 (now abandoned) which was a
continuation of application Ser. No. 07/537,165 filed on Jun. 11,
1990 (now abandoned) which was a division of application Ser. No.
07/373,175 filed on Jun. 28, 1989 (now abandoned) which was a
division of application Ser. No. 07/102,274 filed on Sep. 28, 1987
(now U.S. Pat. No. 4,865,664) which was a continuation of
application Ser. No. 06/797,176 filed on Nov. 8, 1985 (now
abandoned) which was a division of application Ser. No. 06/672,065
filed on Nov. 16, 1984 (now abandoned).
Claims
We claim:
1. A method of producing a thick amorphous alloy strip by ejecting
a molten metal onto a surface of a moving cooling substrate for
quenching, comprising the steps of:
providing said moving cooling substrate by using a single-roll
cooling process;
ejecting under pressure a first molten metal through a first nozzle
opening onto the moving cooling substrate to form a first molten
metal puddle portion;
drawing out first molten metal from the first molten metal puddle
portion to form a strip, by moving the moving cooling substrate in
a predetermined direction;
ejecting under pressure a second molten metal having the same
composition as the first molten metal through a second nozzle
opening spaced 0.5 to 4 mm from the first nozzle opening along the
moving direction of the cooling substrate and formed in parallel
with the first nozzle opening, said second molten metal being
ejected on the surface of the strip, the strip being incompletely
solidified, with said second molten metal forming a second molten
metal puddle portion, wherein the second molten metal of the second
molten metal puddle portion mixes with non-solidified metal of the
incompletely solidified strip, the non-solidified metal of the
incompletely solidified strip being located at a top portion of
said strip facing said second nozzle opening and forming the
surface of the strip onto which the second molten metal is
ejected;
drawing out second molten metal from the second molten metal puddle
portion to form an initial monolithic strip composed of the second
molten metal and the incompletely solidified strip, the strip being
brought into firm contact with the surface of the moving cooling
substrate due to said ejection under pressure thereby increasing
cooling rate; and
thereby obtaining a monolithic metal strip having a thickness of at
least 50 .mu.m and having a fracture strain of 0.01 or more upon
complete solidification of said strip.
2. A method according to claim 1, wherein said drawing out of the
molten metal is carried out in a pressurized atmosphere.
3. A method according to claim 1, wherein said drawing out of the
molten metal is carried out by increasing an ejecting pressure
thereof during the method.
4. A method according to claim 1, wherein the gap between said
molten metal puddle portions is 4 mm or less.
5. A method according to claim 1, wherein said drawing out of the
molten metal is carried out in a helium atmosphere.
6. A method of producing a thick amorphous alloy strip according to
claim 25 further comprising:
ejecting under pressure at least one subsequent molten metal having
the same composition as the first molten metal through at least one
subsequent nozzle opening spaced 0.5 to 4 mm from the preceding
nozzle opening, said subsequent molten metal being ejected on the
surface of the initial monolithic strip, the initial monolithic
strip being incompletely solidified and having non-solidified metal
located at a top portion of said initial monolithic strip facing
said subsequent nozzle opening and forming the surface of the
initial monolithic strip onto which said subsequent molten metal is
ejected, with said subsequent molten metal forming a subsequent
molten metal puddle portion, wherein the subsequent molten metal of
the subsequent molten metal puddle portion mixes with the
non-solidified metal of the initial monolithic strip; forming a
subsequent monolithic strip by drawing out subsequent molten metal
from said subsequent molten metal puddle portion; thereby obtaining
the monolithic metal strip having a thickness of at least 50 .mu.m
and having a fracture strain of 0.01 or more upon complete
solidification of said strip.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to amorphous alloy strips having a
large thickness and a method for producing the same, more
particularly to amorphous alloy strips having a large thickness
produced by quenching and solidifying molten metal or alloy on a
movable cooling substrate and a method for the same.
2. Description of the Related Art
It is well known to use a melt spin process to continuously produce
amorphous strips from molten metal or alloy. In the melt spin
process, molten metal is deposited onto a cooling substrate, e.g.,
the surface of annular chill roll, through a nozzle or nozzles. The
molten metal is quenched and solidified by the cooling substrate,
resulting in a continuous metal strip or wire.
In the melt spin process, the cooling rate is so high that, if the
composition is suitably selected, an amorphous metal or alloy
having substantially the same structure as the molten metal can be
obtained. An amorphous metal or alloy has unique properties
valuable for practical applications.
There are, however, some difficulties in obtaining wide strips.
Important factors in the production of an amorphous metal or alloy
are the shape of the nozzle, the relative arrangement of the nozzle
and cooling substrate, the ejecting pressure of the molten metal
through the nozzle, and the moving rate of the cooling substrate.
To increase the width of the strip, one must meet severe conditions
for each of the above.
A continuous casting method for a metallic amorphous strip and an
apparatus for producing a wide strip are disclosed in Japanese
Unexamined Patent Publication (Kokai) No. 53-53525. The method
includes the steps of directing a slotted nozzle having a
rectangular opening to a cooling substrate (roll or belt) with a
gap of from about 0.03 to about 1 mm therebetween, advancing the
cooling substrate at a speed to provide a peripheral velocity of
from about 100 to about 2000 meters per minute, and ejecting molten
metal to the chill surface of the cooling substrate through the
slotted nozzle. The molten metal is quenched in contact with the
chill surface at a rapid quenching rate and solidifies into a
continuous amorphous metal strip. In this method, there is no limit
on the width of the amorphous metal strip, in principle.
Restrictions on the cooling rate also make it difficult to obtain a
thick strip. The problem of thickness of increasing the thickness
of the strip has not been solved up until now. This limit on the
thickness of the strip applies not only to amorphous metal
requiring severe cooling conditions, but also to crystalline metal
not requiring the same. The principal method adoptable to try to
form a metal strip having a large thickness in the conventional
continuous molten metal quenching process is to increase the
advancing length of the puddle formed on the cooling substrate with
respect to the advancing speed of the cooling substrate. In actual
production of an amorphous metal strip, any one of the following
means or combinations thereof may be considered to achieve this
increase: The means are
1. To enlarge the width of the nozzle opening
2. To increase the forcing pressure
3. To increase the gap between the nozzle and the chill surface
4. To decrease the advancing speed of the cooling substrate
The present inventors experiments to produce an amorphous metal
strip having a large thickness by using the above four means, but
could not obtain good results. They found that there is a limit on
thickness due to the type of metal or alloy and the material of the
cooling substrate and that an unreasonable increase in thickness
leads to an undesired shape and deterioration of the strip.
Excessive molten metal, specifically, adheres to the nozzle and
solidifies thereon. The solidified metal, which contacts the
advancing chill surface, leads to nozzle breakage. Also, when a
thick strip is produced by the above four means, the free surface
of the metal strip is exposed to the atmosphere for a longer time,
resulting in an undesired appearance, such as a rough surface,
furrows, and coloring. Generation of such phenomena, in the case of
an amorphous alloy, means also that crystal is formed on the
surface layer, even if the crystal cannot be detected by X-ray
diffraction. This reduces the ductility, the magnetic properties
such as coercive force and core loss , and other properties of the
amorphous alloy.
IEEE Trans., May 18 (1982) page 1385, discloses that if the strip
thickness at which the coercive force begins to increase is defined
as the critical strip thickness at which crystallization commences,
the greatest critical strip thickness shown by an Fe-Si-B system
alloy is 42 .mu.m of Fe.sub.76 -B.sub.10 -Si.sub.10. According to
investigations by the present inventors, with Fe.sub.80.5
Si.sub.6.5 B.sub.12 C.sub.1 of a width of 25 mm, the critical strip
thickness is 32 .mu.m. Further U.S. Pat. No. 4,331,739 discloses
F.sub.40 Ni.sub.40 P.sub.14 B.sub.6 of a width of 5 cm, a thickness
of 0.05 mm (50 .mu.m), and isotropic tensile properties.
Recently, an Fe base alloy strip having a width of 25.4 mm and a
thickness of 82 .mu.m was reported (Journal of Applied Physics vol.
5, No. 6 (1984) P. 1787). According to the report, however, this
alloy strip, of Fe.sub.80 B.sub.14.5 Si.sub.3.5 C.sub.2 showed the
existence of 5% or less crystals under an X-ray diffraction test.
As a consequence, the alloy strip as cast shows considerable
brittleness. The fracture strain by bending stress of an 82 .mu.m
thick Fe.sub.80 B.sub.14.5 Si.sub.3.5 C.sub.2 alloy is 0.006. The
fracture strain .epsilon..sub.f is usually represented by the
equation .epsilon..sub.f =t/(2r-t), wherein t is the strip
thickness and r is the bending radius.
The more amorphous the alloy, the greater the fracture strain. A
substantially amorphous alloy has a crystallization ratio of 1% or
less as cast. The crystallization ratio is defined as follows:
wherein I is the diffraction intensity on a specified crystal face
for example (110) face of a sample of a strip as cast, Io is the
diffraction intensity on the same crystal face of a standard
amorphous sample, and Ic is the diffraction intensity on the same
crystal face upon complete crystallization.
SUMMARY OF THE INVENTION
The main object of the invention is to provide an Fe base alloy
strip having a large sheet thickness and width.
Another object of the present invention is to provide an Fe base
alloy strip having a large sheet thickness and width and having
improved mechanical properties, particularly, bending fracture
strain.
A further object of the present invention is to provide a method
for producing an amorphous metal strip having a large sheet
thickness and width and having improved properties.
According to the present invention, there is provided an Fe base
amorphous alloy strip having a sheet thickness of from 50 to 150
.mu.m and a sheet width of at least 20 mm. The strip is produced by
depositing molten metal onto the surface of a moving annular chill
body in what is called a "Single-roll cooling process". This strip
preferably has a surface roughness of the free surface and the
constrained surface to the roll below 0.5 mm when measured by Japan
Industrial Standard (JIS)-B0601. It also preferably has a fracture
strain .epsilon..sub.f of 0.01 or more. In the present invention,
"free surface" is defined as the strip surface which is not
directly contacted with the chill surface of the roll during the
production of amorphous strips. On the other hand, "constrained
surfact to the roll" is defined as the strip surface which is in
direct contact with the chill surface of the roll.
There is further provided a method for producing an amorphous metal
strip by jetting a molten metal onto a chill surface of a rotating
annular chill body for quenching, including the steps of drawing
out a first molten metal on the moving chill surface through a
first molten metal puddle portion to make a first strip; drawing
out a second molten metal over the first strip as in a not
completely solidified state of through a second molten metal puddle
portion so as to make a second strip, the first strip being brought
into strong contacted with the moving chill surface due to the
pressure generated by the second puddle portion; and drawing out
subsequent molten metals through further portions so as to make
subsequent strips until the required sheet thickness is obtained.
Tha resultant strip is a monolithic state strip.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph illustrating the relationship between strip
thickness and fracture strain in amorphous alloy strips according
to the present invention and that of conventional alloy strips;
FIGS. 2 and 3 are graphs illustrating the relationships between
strip thicknesses and heat of crystallization and between strip
thicknesses and magnetic flux density;
FIG. 4 is a view explaining a method according to the present
invention;
FIGS. 5 and 6 are views explaining nozzles used in a method
according to the present invention;
FIG. 7 is a view illustrating a method for producing a strip
according to the present invention;
FIG. 8 is a view of a bottom surface of a nozzle with nozzle
openings used in the present invention;
FIGS. 9A and 9B are views illustrating the surface roughness of a
free surface and constrained surface of an amorphous alloy strip
according to the present invention;
FIGS. 9C and 9D are views illustrating the surface roughness of a
free surface and constrained surface of comparative alloy
strips;
FIGS. 10A and 10B are scanning electron micrographs illustrating a
magnetic domain structure of a free surface of an amorphous alloy
strip as cast according to the present invention and a conventional
alloy strip;
FIGS. 11A and 11B are scanning electron micrographs illustrating a
magnetic domain structure of a free surface, after annealing, of an
amorphous alloy strip according to the present invention and a
conventional alloy strip; and
FIGS. 12A and 12B are views illustrating the X-ray diffraction
intensity of an amorphous strip having a thickness of 100 .mu.m
according to the present invention and a conventional strip having
a thickness of 30 .mu.m.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The Fe base amorphous alloy strip according to the present
invention has a smoother constrained surface and free surface
compared with a strip produced by a conventional process. As shown
in Table 1, the centerline average surface roughness Ra at a cut
off value of 0.8 mm measured by JIS B0601 is below 0.5 .mu.m for
both the constrained surface and free surface. This is smaller,
i.e., superior, compared with the 0.6 to 1.3 .mu.m of a
conventional constrained surface and the 0.6 to 1.5 .mu.m of a
conventional free surface.
With respect to the relationship between the surface roughness and
magnetic properties, a smoother surface roughness means an improved
coercive force, magnetic flux density and space factor. On the
other hand, a thicker strip can be used for a large transformer as
like a siliconsteel sheet and can be easily handled without
deterioration of magnetic properties.
For example, since the amorphous alloy strip according to the
present invention has a large thickness and smooth surface, the
space factor is very high. The space factor of a conventional
amorphous alloy strip having thinner thickness ranges from 75% to
85%, while, the space factor of an amorphous alloy strip according
to the present invention ranges from 85% to 95%. Use of a material
having a high space factor for, e.g., a magnetic core enables
realization of a smaller core. Thus, a material having a high space
factor is advantageous in practical use.
Even though the amorphous alloy strip of the present invention has
a large thickness, no deterioration of its properties occur. The
alloy strip remains substantially amorphous therethrough and so
maintains its specific amorphous properties. For example, while a
magnetic flux density at 50 Hz and 1 Oe of 1.53 tesla can be
obtained in a conventional amorphous alloy strip of Fe.sub.80.5
Si.sub.6.5 B.sub.12 C.sub.1 (at %) having a thickness of 25 .mu.m
and a width of 25 mm, the same magnetic flux density can be
obtained in an amorphous alloy strip of Fe.sub.80.5 Si.sub.6.5
B.sub.12 C.sub.1 having a thickness of 65 .mu.m and a width of 25
mm according to the present invention. It is clear that no
deterioration in magnetic flux density occurs.
The Fe base amorphous alloy strip by which the second object can be
obtained is at least 50 .mu.m thick, at least 20 mm wide, and has a
bending fracture strain (.epsilon..sub.f) of 0.01 or more,
generally 0.15 or more, as mentioned above. On the other hand, the
bending fracture strain .epsilon..sub.f in a conventional strip
having the same thickness is below 0.01. Thus, the strip of the
present invention has a 50% larger fracture strain than a
conventional strip.
The reason why the strip of the present invention has improved
mechanical properties will be hereinafter explained.
It is well known that the properties of an amorphous alloy strip
depend on the sheet thickness. The sheet thickness of the strip
will change the properties through thermal hysteresis. The decrease
of the fracture strain which arises with an increase of the sheet
thickness derives from the slower cooling rate of the strip during
and after solidification. The slower cooling rate occurs as the
sheet thickness of the strip become larger. Namely, when the
thickness of the strip become larger, the amorphous structure of
the strip is relaxed so that the structure of the strip becomes
crystal, whereby the strip becomes brittle.
From this point of view, the strips of the present invention are
produced so that the cooling rate is not decreased. In the present
invention, although the sheet thickness of the strip is enlarged,
the cooling rate during and after solidification is substantially
the same phenomena as in the case of conventional strips having a
sheet thickness of 30 .mu.m. Therefore, the time during which the
strips of the present invention are relaxed becomes short, with the
result that they have improved mechanical properties, particularly,
a large bending fracture strain.
FIG. 1 is a graph illustrating the relationship between sheet
thicknesses and fracture strain in amorphous alloy strips according
to the present invention and that of conventional alloy strips. The
amorphous alloy strips used consist of Fe.sub.80.5 Si.sub.6.5
B.sub.12 C.sub.1.
As shown in FIG. 1, when the sheet thickness of conventional strips
exceeds 45 .mu.m, the fracture strain .epsilon..sub.f rapidly
declines. When the sheet thickness is 50 .mu.m, the fracture strain
is about 0.01. However, in the strips of the present invention,
when the sheet thickness of the strips is 55 .mu.m, the fracture
strain is 1. Namely, even if the strips of the present invention
are bent at an angle of 180.degree., they will not fracture. In the
case of a sheet thickness of 65 .mu.m, 180.degree. bending is
impossible, but a fracture strain of 0.03 is obtained. In the case
of a sheet thickness of 75 .mu.m, the fracture strain declines to
0.02. However, even in the case of a sheet thickness of 110 .mu.m,
the fracture strain is above 0.01.
FIGS. 2 and 3 are graphs illustrating the relationships between
strip thicknesses and heat of crystallization and between strip
thicknesses and magnetic flux density.
As shown in FIG. 2, in an amorphous alloy strip of the present
invention consisting of Fe.sub.80.5 Si.sub.6.5 B.sub.12 C.sub.1,
the heat of crystallization .DELTA.H (J/g) is constant in cases of
sheet thicknesses ranging from 20 .mu.m to 70 .mu.m. When the sheet
thickness exceeds 70 .mu.m, the heat of crystallization is rapidly
lowered. On the other hand, as shown in FIG. 2 (not shown) in the
above-mentioned Journal of Applied Physics, the heat of
crystallization is rapidly lowered at a sheet thickness of about 17
.mu.m. This means that the amorphous substance ratio of the strip
of the present invention is higher than that of a conventional
strip in a wide range of sheet thicknesses.
Further, as shown in FIG. 3, in a strip of the present invention
having a sheet thickness below about 70 .mu.m, the core loss
W.sub.13/50 (W/kg) is larger than that of a conventional strip of
about 20 to 30 .mu.m. However the magnetic properties, for example,
the magnetic flux density, in a strip of the present invention is
substantially the same as in a conventional strip. We core loss
increases due to the increase of the domain width, not to
occurrence of crystals.
The amorphous alloy strip of the present invention includes Fe as a
main component and includes one or more of boron, silicon, carbon,
phosphorus, and the like as a metalloid. In accordance with the
properties required, part of the iron may be substituted by another
metal. For example, if a magnetic property is required, half the
iron may be replaced with cobalt and/or nickel. In turn, in order
to improve the magnetic property, one or more of molybdenum,
niobium, manganese, and tin may be added. In order to improve
corrosion resistance, one or more of molybdenum, chromium,
titanium, zirconium, vanadium, hafnium, tantalum, and tungsten may
be added. In order to improve mechanical properties, manganese,
aluminum, copper, tin, or the like may be added. The content of
iron may range from 40% to 82% (at %), boron from 8% to 17%,
silicon from 1% to 15%, carbon below 3%, and residual elements
below 10% in total. Above ranges of respective composition are
selected in accordance with use.
With the amorphous alloy strips of the present invention are used
as a core material, the strips are preferably composed of Fe.sub.a
B.sub.b Si.sub.c C.sub.d. The ranges of a, b, c, and d are
respectively 77 to 82, 8 to 15, 4 to 15, and 0 to 3.
The amorphous alloy strips according to the present invention are
advantageously used for transformers, spring materials, corrosion
resistant materials, sensors, structural materials, and the
like.
A method for producing an amorphous alloy strip according to the
present invention will now be explained in detail with reference to
the drawings.
FIG. 4 is a view explaining the method according to the present
invention, FIGS. 5 and 6 are views explaining nozzles used in the
method, and FIG. 7 is another view illustrating the method
according to the present invention.
As shown in FIGS. 4 and 5, a metal substance in usually melted by
using a crucible 2. After that, molten metal 6 is flowed out on a
cooling substrate 1, which moves in the direction of the arrow,
through openings 4a and 4b of a nozzle 3.
As shown in FIG. 7, a puddle 5b composed of molten metal 6 flowed
out through the second opening 4b is formed on an incompletely
solidified strip 7a drawn out from a puddle 5a flowed out through
the first opening 4a and formed on the cooling substrate 1. The
strip 7b made of the puddle 5b is moved to the strip 7a. Since the
strip 7a has sufficient cooling ability, the strip 7b is rapidly
cooled together with the strip 7a, whereupon a monolithic sheet
formed by the strips 7b and 7a is obtained.
As a result, strips having a large thickness can be continuously
produced.
According to the present invention, the flowing out of the molten
metal on the chill surface is preferably carried out under a
pressurized atmosphere of, for example, 0.5 to 2 kg/cm.sup.2 larger
pressure than ambient pressure anbient pressure. This pressure
increases the contact force of the molten metal with the chill
surface.
In the present method, at the stage of commencement of the
solidification of metal, the molten metal contacts with the cooling
substrate with a thermal effect. The cooling rate of the strip in
the range of temperature most important for the properties of the
strip is remarkably increased, enabling formation of a strip having
twice or more the sheet thickness of strips produced by the
conventional method.
According to the present invention, when, for example, multiple
openings of nozzles are used, the opportunities for oxidation of
the free surface of the strips and crystallization of the strips
are considerably decreased. Thus, an amorphous alloy strip having a
large sheet thickness according to the present invention does not
suffer from deterioration of properties or undesired shape.
In the present invention, it is preferable that the atmosphere
around the puddle be inert gas such as helium.
The gap between one puddle and a subsequent puddle may be selected
so that when the strip portion formed via the one puddle contacts
the strip portion formed via the subsequent puddle the former has
not yet completely solidified. The most suitable gap is usually 4
mm or less. The width direction of the opening of the nozzle is
oriented in parallel to the moving direction of the cooling
substrate.
The size of the opening and the gap between openings may be
selected as follows.
______________________________________ Length (1) of opening:
Substantially the same as the width of strips Width (w) of opening:
Maximum 0.8 mm Minimum about 0.2 mm Distance (d) between openings:
determined in accordance with shape and size of the opening and
required sheet thickness; usually 0.5 to 4 mm
______________________________________
To increase the sheet thickness of the strip, a plurality of
openings having a small width may be used while keeping the gap
between the openings small.
The present inventors have found that there is a certain range of
sheet thickness in which strips having improved shapes and
properties can be formed by a certain number of openings. For
strips consisting of iron and metalloid, the range is 15 to 45
.mu.m for a single opening of a width of 0.4 mm; 30 to 60 .mu.m for
two openings; and 40 to 70 .mu.m for three openings. These sheet
thicknesses can be further increased by increasing the ejecting
pressure during the casting.
Using this method, therefore, there should be no limit as to the
sheet thickness in principle. However, there is an actual limit on
the sheet thickness of the strips produced by the present invention
due to the thermal conductivity and critical cooling rate of
amorphous material. Still, the upper limit of the sheet thickness
is remarkably raised as compared to the conventional method.
EXAMPLE 1
Alloys consisting of compositions described in Table 1 were cast in
an amorphous alloy strip having a width of 25 mm by using a single
roll made of copper and using three-slotted nozzles (w: 0.4 mm, l:
25 mm, d: 1 mm) as shown in FIG. 8. The production controls were an
ejecting pressure of molten metal of 0.20 to 0.35 kg/cm.sup.2, a
roll speed of 20 to 28 m/sec, and a gap between the nozzle and roll
of 0.15 to 0.25 mm.
The sheet thickness, surface roughness, and space factor of the
obtained amorphous alloy strips of the various compositions are
shown in Table 1. Also shown are the typical levels of conventional
strips produced by using a single roll. As shown in Table 1, in the
strips of the present invention, the sheet thickness is large, the
surface roughness small, and the space factor high compared to
conventional strips.
FIGS. 9A and 9B are views illustrating the surface roughness of a
free surface and a constrained surface of an amorphous alloy strip
according to the present invention. FIGS. 9C and 9D are views
illustrating the surface roughness of a free surface and a
constrained surface of comparative alloy strips. The amorphous
alloy strip of the present invention has a sheet thickness of 62
.mu.m, while the comparative alloy strip has a sheet thickness of
40 .mu.m.
FIGS. 10A and 10B are scanning electron micrographs illustrating
the magnetic domain structure of a free surface of amorphous alloy
strip No. 1 in Table 1 according to the present invention and a
conventional alloy strip. The conventional alloy strip has a
complex maze pattern of a magnetic domain structure, while the
alloy strip of the present invention has, as cast, 180.degree.
magnetic domains oriented in the same direction.
FIGS. 11A and 11B are scanning electron micrographs illustrating
the magnetic domain structure of a free surface, after annealing,
of an amorphous alloy strip according to the present invention and
a conventional alloy strip. The amorphous alloy strip according to
the present invention shown in FIG. 11A has a magnetic domain of a
larger width than in the conventional alloy strip shown in FIG.
11B.
EXAMPLE 2
Alloys consisting of compositions described in Table 2 were cast
into amorphous alloy strips having a width of 25 mm by using the
same single roll, nozzle, 15 and production conditions as explained
in Example 1.
The sheet thickness, surface roughness, and space factor of the
obtained amorphous alloy strips of the various compositions are
shown in Table 2.
As explained in Example 1, the alloy strips according to the
present invention have improved properties.
TABLE 1
__________________________________________________________________________
Surface roughness Sheet Ra (.mu.m) Space thickness Constrained Free
factor B.sub.1 No. Composition (at %) .mu.m surface surface (%) (T)
__________________________________________________________________________
Strips of 1 Fe.sub.80.5 B.sub.12 Si.sub.7.5 62 0.41 0.44 90 1.52
the present 2 Fe.sub.80.5 B.sub.12 Si.sub.6.5 C.sub.1 65 0.38 0.41
91 1.53 invention 3 Fe.sub.78 B.sub.10 Si.sub.12 60 0.38 0.40 88
1.49 4 Fe.sub.78 B.sub.10 Si.sub.10 C.sub.2 62 0.29 0.38 90 1.50 5
Fe.sub.70.5 B.sub.12 Si.sub.7.5 Co.sub.10 65 0.38 0.40 91 1.61 6
Fe.sub.70.5 B.sub.12 Si.sub.7.5 Ni.sub.10 68 0.35 0.38 92 1.40 7
Fe.sub.75.5 B.sub.12 Si.sub.7.5 Mo.sub.5 71 0.40 0.46 92 0.97 8
Fe.sub.75.5 B.sub.12 Si.sub.7.5 Cr.sub.5 69 0.37 0.42 88 1.03 9
Fe.sub.75.5 B.sub.12 Si.sub.7.5 Nb.sub.5 70 0.30 0.39 90 1.05 10
Fe.sub.65.5 B.sub.12 Si.sub.7.5 Co.sub.10 Mo.sub.5 72 0.39 0.37 93
1.05 11 Fe.sub.65.5 B.sub.12 Si.sub.7.5 Ni.sub.10 Mo.sub.5 70 0.33
0.37 92 0.93 12 Fe.sub.65.5 B.sub.12 Si.sub.7.5 Ni.sub.10 Cr.sub.5
66 0.25 0.32 90 0.90 13 Fe.sub.65.5 B.sub.12 Si.sub.7.5 Co.sub.10
Cr.sub.5 57 0.36 0.40 90 1.03 14 Fe.sub.60.5 B.sub.12 Si.sub.7.5
Ni.sub.5 Co.sub.10 Cr.sub.5 55 0.38 0.46 89 1.01 Comparative 15
Fe.sub.80.5 B.sub.12 Si.sub.7.5 36 0.81 0.60 84 1.52 strips 16
Fe.sub.80.5 B.sub.12 Si.sub.6.5 C.sub.1 40 0.75 0.93 83 1.53 17
Fe.sub.78 B.sub.10 Si.sub.12 23 0.64 0.63 83 1.48
__________________________________________________________________________
B.sub.1 : Magnetic flux density in 50 Hz, 1 Oe Ra: Cutoff value 0.8
mm, measured length 8 mm Space factor: About 700 g strip was wound
up on a reel having outer diameter of 40 mm. ##STR1## - Wherein the
calculated weight is (R.sup.2 - r.sup.2) .pi. R: outer diameter of
ring r: inner diameter of ring w: width .rho.: specific weight
TABLE 2
__________________________________________________________________________
Surface roughness Sheet Ra (.mu.m) Space thickness Constrained Free
factor No. Composition (at %) .mu.m surface surface (%)
__________________________________________________________________________
Strips of 1 Fe.sub.80 P.sub.13 C.sub.7 65 0.39 0.41 91 the present
2 Fe.sub.72 P.sub.13 C.sub.7 Cr.sub.8 62 0.45 0.44 90 invention 3
Fe.sub.70 P.sub.10 C.sub.10 Cr.sub.10 59 0.38 0.38 94 4 Fe.sub.50
P.sub.13 B.sub.7 Ni.sub.30 67 0.48 0.42 90 5 Fe.sub.50 P.sub.13
B.sub.7 Co.sub.30 70 0.32 0.37 93 6 Fe.sub.76 P.sub.13 C.sub.3
Si.sub.4 Cr.sub.4 62 0.41 0.39 91 Comparative 7 Fe.sub.80 P.sub.13
C.sub.7 28 0.68 0.61 84 strips 8 Fe.sub.80 P.sub.13 C.sub.7 33 0.78
0.87 82 9 Fe.sub.80 P.sub.13 C.sub.7 41 0.81 0.90 81
__________________________________________________________________________
EXAMPLE 3
An alloy consisting of Fe.sub.80.5 Si.sub.6.5 B.sub.12 C.sub.1 (at
%) was cast into an amorphous alloy strip by using substantially
the same production conditions explained in Example 1.
The sheet thickness, bending fracture strain .epsilon..sub.f, and
other properties are shown in Table 3. Also shown are the
properties of Co conventional alloy strip produced by using a
single-slotted nozzle (d: 0.7 mm, 1: 25 mm).
TABLE 3 ______________________________________ Sheet Space
thickness factor (.mu.m) .epsilon..sub.f Ra (.mu.m) (%)
______________________________________ Strip of 65 0.03 Roll Free
91 the present surface surface invention 0.35 0.40 Comparative 50
0.0065 0.80 1.05 83 strip
______________________________________
EXAMPLE 4
An alloy consisting of Fe.sub.80.5 Si.sub.6.5 B.sub.12 C.sub.1 was
cast into an amorphous alloy strip by using a single roll and a
four-slotted nozzle (w: 0.4 mm, 1: 25 mm, d: 1 mm) and an ejecting
pressure of molten metal of 0.3 kg/cm.sup.2. During the casting,
the roll speed was changed from 25 m/sec to 18 m/sec. At the time
the roll speed was changed, the free surface of the strip was
pressurized by helium gas. A comparative strip was also cast by
using the same nozzle as explained in Example 3. The roll speed was
also changed as mentioned above.
The obtained properties are shown in Table 4.
TABLE 4 ______________________________________ Sheet Space
thickness factor (.mu.m) .epsilon..sub.f Ra (.mu.m) (%)
______________________________________ Strip of 75 0.02 Roll Free
93 according to surface surface the present 0.32 0.35 invention
Comparative 56 0.005 0.82 1.13 85 strip
______________________________________
EXAMPLE 5
An alloy consisting of Fe.sub.80.5 Si.sub.6.5 B.sub.12 C.sub.1 was
also cast into an amorphous alloy strip by using the two-slotted
nozzle as shown in FIG. 5 (l: 25 mm, w: 0.4 mm, d: 1 mm) and a
single roll made of copper. The production controls were an
ejecting pressure of molten metal of 0.22 kg/cm.sup.2, a roll speed
of 25 m/sec, and a gap between the nozzle and roll of 0.15 mm. The
sheet thicknesses of the obtained strips were an average 45 .mu.m.
Further crystallization was not found in the strips by X-ray
diffractometry. The magnetic properties of the strip according to
the present invention are substantially the same as those of a
conventional strip produced by using a single nozzle, as shown in
Table 5.
TABLE 5 ______________________________________ Sheet Magnetic flux
thickness Core loss W.sub.1.3/50 density B.sub.1 (.mu.m) (Watt/kg)
(Tesla) ______________________________________ 35 0.23 1.32 26 0.10
1.51 45 0.11 1.52 ______________________________________ (Heat
treatment: 380.degree. C. .times. 1 hr)
EXAMPLE 6
An alloy consisting of Fe.sub.80.5 Si.sub.6.5 B.sub.12 C.sub.1 was
cast into an amorphous alloy strip by using a three-slotted nozzle
as shown in FIG. 6 (l: 25 mm, w: 0.4 mm, d.sub.1 =d.sub.2 : 1.0 mm)
and a single roll. The production conditions were the same as
explained in Example 5. The sheet thickness of the obtained strips
was an average 60 .mu.m. Further, non-crystallization was found in
the strips. The magnetic properties, shown in Table 6, are
substantially the same as the strips produced by the conventional
method.
TABLE 6 ______________________________________ Sheet Magnetic flux
thickness Core loss W.sub.1.3/50 density B.sub.1 (.mu.m) (Watt/kg)
(Tesla) ______________________________________ 62 0.125 1.53
______________________________________
EXAMPLE 7
An alloy consisting of 6.5 wt% silicon steel was cast into an
amorphous alloy strip by using a three-slotted nozzle as shown in
FIG. 6 (l: 25 mm, w: 0.4 mm, d.sub.1 =d.sub.2 : 1.5 mm) and a
single roll made of iron. The production conditions were an
ejecting pressure of molten metal of 0.22 kg/cm.sup.2, a roll speed
of 22 m/sec, and a gap between the nozzle and the roll of 0.2 mm.
The sheet thickness and the crystal grain size of the obtained
strips were an average 63 .mu.m and 10 .mu.m, respectively. The
surface property and the shape of the strip were remarkably
improved.
EXAMPLE 8
An amorphous stainless steel strip consisting of C.sub.0.06
Si.sub.0.6 Mn.sub.0.5 P.sub.0.025 S.sub.0.005 (wt%) was produced by
using a single roll made of iron and the nozzle in Example 7. The
production conditions were the same as explained in Example 7.
The sheet thickness and the crystal grain size were an average 58
.mu.m and 5 .mu.m, respectively. The properties were improved.
EXAMPLE 9
An amorphous alloy strip consisting of Fe.sub.80 Mo.sub.4 B.sub.12
C.sub.4 (at %) was produced by using a four-slotted nozzle (l: 25
mm, w: 0.4 mm, d: 1.0 mm). The production conditions were a first
ejecting pressure of molten metal of 0.08 kg/cm.sup.2, a second
ejecting pressure of 0.22 kg/cm.sup.2, a roll speed of 12 m/sec,
and a gap between the nozzle and the roll of 0.15 to 0.18 mm.
The sheet thickness of the obtained strip was an average 100 .mu.m.
The strips were found to be amorphous by x-ray diffractometry.
FIGS. 12A and 13 are views illustrating the X-ray diffraction
intensity of an amorphous strip having a thickness of 100 .mu.m
according to the present invention and a conventional strip having
a thickness of 30 .mu.m.
It can be see from FIGS. 12 and 13 that the X-ray diffraction
intensity of the strip of the present invention is substantially
the same as that of a conventional strip.
EXAMPLE 10
An amorphous alloy strip consisting of Fe.sub.80 Mo.sub.4 B.sub.12
C.sub.4 (at %) was produced by using a four-slotted nozzle (1: 25
mm, w: 0.4 mm, d: 1.0 mm). The production conditions were a first
ejecting pressure of molten metal of 0.08 kg/cm.sup.2, a second
ejecting pressure of 0.28 kg/cm.sup.2, a roll speed of 12 m/sec,
and a gap between the nozzle and the roll of 0.15 to 0.18 mm.
The sheet thickness of the obtained strip was an average 120 .mu.m.
The strips were found to be amorphous by X-ray diffractometry. The
X-ray diffraction intensity was substantially the same as that of
the Example 9.
* * * * *